Hydrocarbon recovery volume from a vertically-drilled well can be increased by drilling additional wellbores from that same well. For example, the fluid recovery rate and the well's economic life can be increased by drilling a horizontal, or lateral, interval from a main wellbore into one or more formations. Still further increases in recovery and well life can be attained by drilling multiple horizontal intervals into multiple hydrocarbon-bearing formations.
Oil and gas production from hydrocarbon-bearing geological formations can yield high levels of salt and other elements that can seriously hamper the well production. The well casing extends down into the formation, and includes a plurality of perforations that extend laterally into the formation to permit the hydrocarbons to flow into the main wellbore. Production tubing, which extends through the casing, and packers are then used to conduct the hydrocarbon out of the well.
Salts and other elements from the formation tend to deposit in the production tubing and, more significantly, in the perforations that extend from the casing into the formation. Over time, deposits can accumulate in the perforation walls and along the flow path, significantly reducing the perforation diameters and in turn, reduce the production flow from the well. Also, over the life of the well, its production rate and the amounts of undesirable elements present in the hydrocarbon production varies.
Deposits of salt and other water-soluble elements can be removed and/or prevented by treating the well, such as by flushing the production tubing with solutions in which the deposits are soluble, or by injecting the solutions into the production tubing to dislodge the deposits.
Accordingly, access to the horizontal or lateral wellbores of a well on a maintenance basis is necessary to prolong the useful production life of a well. Sliding sleeves have been installed in multilateral wells adjacent the lateral bores, but manipulation of these units have been time consuming and added to the maintenance expense of a well. For example, before maintenance well tools could be lowered into the lateral wellbore, a coiled-tubing tool had to make a well trip to raise the side door. Next, the maintenance tool was lowered into the well to access the lateral wellbore so that well maintenance can be done. Also, the position of a side door has not been readily discernable from the surface, and must be determined from records concerning the configuration of the well, or an exploratory trip that may simply determine that the side door was in the necessary position.
Accordingly, there is a need for eliminating a downhole trip devoted for simply opening a sliding side door to access a lateral wellbore. Further, a need exists for determining the configuration of the side doors in a multilateral well from the surface without the need to perform an exploratory trip to determine the actual configuration of the well.